1. Field of the Invention
The present invention relates to an electric syringe for a dental anesthetic in which used when injecting an anesthetic in a dental treatment.
2. Description of the Related Art
As a generally used tool for injecting an anesthetic in a dental treatment, there is known a hand-operated syringe. When using the hand-operated syringe, since there is used an extremely fine needle for an anesthetic, there is required a large pushing force when injecting the anesthetic into the gum of a patient and thus there is required a great deal of labor to maintain a constant injection speed. In view of the above, there has been spread an electric syringe for a dental anesthetic (in which hereinafter referred to simply as an electric syringe) that aims at relieving a dental treatment load.
As a related art of such conventional electric syringe, there are known, for example, [An electric syringe for a dental treatment] disclosed in JP-A-7-213610, [An electric injection apparatus for a dental treatment] disclosed in JP-A-2001-70444, and [Mounting apparatus for a receiving cylinder in a cartridge-type injection apparatus for a dental treatment] disclosed in JP-A-2002-191694.
In the electric syringes disclosed in the documents, no consideration is given to the injection speed of the anesthetic; that is, a given quantity of anesthetic is output without controlling the injection speed. In a case where the injection of the anesthetic is started into the gum from such electric syringe, just after needling, a large quantity of anesthetic is injected, to thereby apply an excessively large pressure onto the tissue of the gum around a needlepoint of the needle, which makes a patient feel a pain.
Also, to start the injection of the anesthetic from the electric syringe, it is necessary to press down an operation button by an operator; however, when the operation button is operated in this manner, the vibrations of the operation transmits to the electric syringe and thus the needle is also moved, which also makes the patient feel a pain.
In the conventional electric syringes, the operation button is further requested so as to able to restrict the malfunction thereof.
Further, for the anesthetic, there presently exist two kinds of cartridges: that is, a cartridge for 1.0 ml and a cartridge for 1.8 ml. In the conventional electric syringes, the two kinds of cartridges are used by replacing cartridge holders that respectively hold their associated cartridges.
However, it is not desirable to use the cartridges while replacing a plurality of kinds of cartridge holders, because such usage results in the complicated management of the cartridge holders. Therefore, there have been demands for common use of the cartridge holders.
Also, there has been required a mechanism which is capable of mounting such cartridge holders simply.